In recent years, attention has been paid to minimally invasive surgery represented by abdominal cavity surgery as a method of surgical operation. In the minimally invasive surgery, a surgical instrument such as an endoscope and forceps is inserted through an incised hole about 10 mm made in the surface of the body so as to carry out surgery inside the body. Therefore, this has such an advantage that it can reduce a damage to a patient or a possibility of giving a damage to the patient as compared with ordinary surgical operation.
The forceps used in the minimally invasive surgery does not allow an approach to a diseased part but from a limited direction because its posture is restricted by the incised hole. To execute operations such as gripping, ligation under such a condition simply, bending forceps (manipulator with multiple degrees of freedom), the front end portion of which is bent in multiple directions, have been developed aggressively.
As preceding technology about this kind of the manipulator with multiple degrees of freedom, for example, non-patent documents 1 to 3 can be mentioned. As a specific product, “da Vinci surgical system” manufactured by Intuitive Surgical, Inc. has been well known (refer to non-patent document 4).
Non-patent document 1: T. Oura and other 10 persons, “DEVELOPMENT OF FORCEPS MANIPULATOR SYSTEM FOR LAPAROSCOPIC SURGERY”, JSME [No. 01-4] Robotics and Mechatronics lecture meeting '01 papers, 2A1-D8, 2001
Non-patent document 2: K. Ikuta and other three persons, “RESEARCH ON HYPER-FINGER FOR TELESURGERY OF ABDOMINAL CAVITY”, JSME [No. 00-2] Robotics and Mechatronics lecture meeting '00 paper, 2P1-13-019, 2000
Non-patent document 3: Jeff M. Wndlandt and S. Shankar Sastry, “DESIGN AND CONTROL OF A SIMPLIFIED STEWART PLATFORM FOR ENDOSCOPY”, Proceedings of the 33rd Conference on Decision and Control Lake Buena Vista, Fla.-December 1994, pp. 357-362, 1994
Non-patent document 4: Gary S. Guthart and J. Kenneth Salisbury, Jr., “THE INTUITIVE™ TELESURGERY SYSTEM: OVERVIEW AND APPLICATION”, Proceedings of the 2000 IEEE International Conference on Robotics & Automation San Francisco, Calif. April 2000, pp. 618-621, 2000
A conventional manipulator with multiple degrees of freedom employs wire as a drive power transmitting means from a drive unit. Bending of an articulation and opening/closing of the gripping portion are achieved by winding up wire with a drive unit.
However, driving with wire has following problems.
First, wire needs to be replaced frequently because it can be elongated or broken (for example, in the aforementioned “da Vince” system, replacement of wire is required for about 10 times of surgery) Further, it takes a considerable amount of labor for removal and installation because wire is wound around a gear or pulley. Thus, running cost and maintenance cost increase.
Second, the control accuracy of the articulation or the gripping portion has a limitation because wire is elongated or contracted. Further, wire has such a demerit that it can transmit a drive power only in one direction (pulling direction).
Third, there is a problem that wire is difficult to sterilize and clean. Thus, in the conventional manipulator with multiple degrees of freedom, its sterilization and cleaning before and after surgery are very complicated.